Various brain diseases are known which may be caused particularly by an underdeveloped or ill-developed neural network. Focusing on the fact that patients with underdeveloped or ill-developed brain functions may have the underdeveloped or ill-developed thenar and an abnormal sense of the digit, Patent Document No. 1 discloses an electric stimulator for stimulating the brain of a patient to improve the brain dysfunction by intermittently transmitting electric signals to the brain of the patient by means of the electrodes stuck on the thenar and the digit of the patient.